What is capacitor discharge welding?

Capacitive discharge welding, particularly for large-scale systems, is typically done using film-type capacitors. These capacitors store energy along alternating plates separated by a dielectric film. Charge is stored statically along the lengths of the plates. The basic configuration of the film capacitor is provided in Figure 1.

Are electrolytic capacitors a viable alternative for large capacity CD welding systems?

Electrolytic capacitors (E-caps) offer a potential alternative for large capacity CD welding systems. E-caps incorporate an electrolyte impregnated into a separator. The separator is then sandwiched between anodic and cathodic foils. A dielectric is also used to prevent direct contact of the foils with the electrolyte.

What is capacitive discharge or CD welding?

Capacitive discharge or CD welding is a variant of resistance welding(1,2). The process differs from the conventional variants largely in the type of power supply used. Conventional systems provide some variant of alternating current to a transformer arrangement.

Does a film capacitor provide a similar voltage tolerance for CD welding?

Performance was evaluated based on current range behavior and metallographic response. Conclusions from this work include: to film capacitors – An array was developed to provide similar voltage tolerance and system capacitance to a standard film variant conventionally used for CD welding.

Can e-caps be used for CD welding?

Use of E-caps for CD welding applications does have some challenges. Most notably, E-caps have limits to usable voltages before electrolyte break-down. Current maximum voltages for large capacity E-caps is on the order of 800 V. In addition, E-caps are relatively intolerant to voltage reversals.

What is the difference between alternating current and CD welding?

Conventional systems provide some variant of alternating current to a transformer arrangement. The transformer arrangement produces low voltage, high current power that is suitable for resistance welding. With CD welding, the main energy is stored in a capacitor arrangement.